ECEN_323_Dr. Archibald_Midterm 1_Chapter 1

What components of CPU execution time might be separately tracked and reported?

User CPU time and System CPU time

What is a local area network? A wide area network?

Local Area Network: A network designed to carry data within a geographically confined area, typically within a single building. Wide Area Network: A network extended over hundreds of kilometers that can span a continent.

Which memory or storage technologies are nonvolatile?

Secondary memory Magnetic disk Flash Memory

What role do benchmark sets play in evaluation the performance of computer systems?

They provide a standard "workload" to different computer systems so that performance can be equally evaluated.

What are the "eight great ideas in computer architecture" identified in our text?

Design for Moore's Law Use Abstraction to Simplify Design Make the common case fast Performance vie Parallelism Performance via Pipelining Performance vie Prediction Hierarchy of Memories Dependability via Redundancy

What kinds of memory are said to be volatile?

DRAM

How does a mebibyte differ from a megabyte?

1 Mebibyte (10^6) = 1.04858 Megabyte (2^20) Mebibyte often represents a megabyte. This was created to stand apart from the SI prefix mega. (used for binary)

What is Amdahl's Law, and why is it useful?

A rule stating that the performance enhancement possible with a given improvement is limited by the amount that the improved feature is used. It is quantitative version of the law of diminishing returns. Execution time after improvement = (execution time affected by improvement / amount of improvement) + execution time unaffected

Can you identify examples of each?

Assembly lines in automobile manufacturing (Performance via Pipelining) Suspension bridge cables (Dependability via Redundancy) Aircraft and marine navigation systems that incorporate wind forecasts (Performance vie Prediction) Express elevators in tall buildings (Make the Common Case Fast) Library reserve desk *where high-demand library materials are available for short-term checkout* (Hierarchy of Memories) Increasing the gate area on a CMOS transistor to decrease it's switching time (Performance via Parallelism) Replacing steam-powered catapults in the design of a new aircraft carrier with electromagnetic catapults, knowing that new reactor technology will provide the required extra power (Design for Moore's Law) Building self-driving cars whose control systems make use of existing sensor systems already in smart vehicles, such as lane departure systems and cruise control systems. (Use Abstraction to Simplify Design)

What is the best way to measure computer performance?

By throughput and response time.

What is the "classic CPU performance equation" and what aspects of the hardware and software affect each of its terms?

CPU time = Instruction count * CPI * Clock cycle time OR CPU time = (Instruction count * CPI) / Clock rate

What are the distinguishing characteristics of computing in the "Post-PC era"?

Can you define these terms: personal mobile devices, Cloud Computing, Software as a Service?

What was the "power wall" that computer designers ran into, and how did their designs change as a result?

Computers ran into the program that there was a limit for cooling commodity microprocessors. This caused for battery life to become the new targeted valuable resource.

What is the difference between elapsed time and CPU execution time?

Elapsed time: Also called System Performance. User CPU time & system CPU time CPU execution time: Also called CPU time. The actual time the CPU spends computing for a specific task.

What steps are involved in the translation of a program from a high-level language to a form the hardware can understand?

High-level language -> <Compiler> -> Assembly language -> <Assembler> ->machine language

What advantages do high-level languages offer, relative to programming in assembly language or machine language?

High-level languages are much easier to interpret, and don't force the programmer to think completely like a computer. This is an example of the power of abstraction.

What are the five classic components of a computer?

Input Output Memory Datapath (*Processor) Control (*Processor)

What precisely does it mean if "computer X is n times faster than computer Y"?

It has a lower Execution Time. That ExecutionY > ExecutionX.

What other new terms are introduced for common sizes, and what ambiguity do they resolve?

Kibibyte, mebibyte, gibibyte, tebibyte, bebibyte, exbibyte, zebibyte, yobibyte. They resolve the ambiguity of using base 10 or base 2. (Generally meaning the use of binary).

What three application classes does our text divide computers into, and what are the key characteristics of each?

Personal Computers (PCs) Servers Embedded Computers

Can you define these terms: personal mobile devices, Cloud Computing, Software as a Service?

Personal Mobile Devices: "Are small wireless devices to connect to the Internet; they rely on batteries for power, and software is installed by downloading apps. Conventional examples are smart phones and tablets. Cloud Computing: Refers to large collections of servers that provide services over the Internet; some providers rent dynamically varying numbers of servers as a utility. Software as a Service: Delivers software and data as a service over the Internet, usually via a thin program such as a browser that runs on local client devices, instead of binary code that must be installed, and runs wholly on that device. Examples include web search and social networking.

How does the primary memory differ from the secondary memory?

Primary Memory: Memory used to hold programs while they are running; typically consists of DRAM in today's computers. Secondary Memory: Nonvolatile memory used to store programs and data between runs; typically consists of flash memory in PMDs and magnetic disks in servers.

What key roles does systems software play in modern computer systems?

Systems Software: Software that provides services that are commonly useful, including operating systems, compilers, loaders, and assemblers.

How are performance and execution time related?

The faster execution time, the better "performance" a computer has, because it is speed at which the computer can complete a task. PERFORMANCE = 1/EXECUTION TIME

On typical systems, how does a processor change what is visible on a graphics display?

The image is composed of a matrix of picture elements, or pixels, which can be represented as a matrix of bits, called a bit map. Depending on the size of the screen and the resolution, the display matrix in a typical tablet ranges in size from 1024×768 to 2048×1536. A color display might use 8 bits for each of the three colors (red, blue, and green), for 24 bits per pixel, permitting millions of different colors to be displayed. The computer hardware support for graphics consists mainly of a raster refresh buffer, or frame buffer, to store the bit map. The image to be represented onscreen is stored in the frame buffer, and the bit pattern per pixel is read out to the graphics display at the refresh rate. Figure 1.6 shows a frame buffer with a simplified design of just 4 bits per pixel.

What are key steps in the manufacturing of integrated circuits?

The manufacturing process for integrated circuits is critical to the cost of the chips and hence important to computer designers. Figure 1.12 shows that process. The process starts with a silicon crystal ingot, which looks like a giant sausage. Today, ingots are 8-12 inches in diameter and about 12-24 inches long. An ingot is finely sliced into wafers no more than 0.1 inches thick. These wafers then go through a series of processing steps, during which patterns of chemicals are placed on each wafer, creating the transistors, conductors, and insulators discussed earlier. Today's integrated circuits contain only one layer of transistors but may have from two to eight levels of metal conductor, separated by layers of insulators. A single microscopic flaw in the wafer itself or in one of the dozens of patterning steps can result in that area of the wafer failing. These defects, as they are called, make it virtually impossible to manufacture a perfect wafer. The simplest way to cope with imperfection is to place many independent components on a single wafer. The patterned wafer is then chopped up, or diced, into these components, called dies and more informally known as chips. Figure 1.13 shows a photograph of a wafer containing microprocessors before they have been diced; earlier, Figure 1.9 shows an individual microprocessor die.

What evidence do you see of the ongoing "computer revolution"?

World wide web Computers in automobiles Cell Phones Human genome project Search Engines "Each time the cost of computing improves by another factor of 10"